Carbon dangling-bond center (carbon Pb center) at 4H-SiC(0001)/SiO2 interface

Abstract

We identify a carbon dangling-bond center intrinsically formed at thermally oxidized 4H-SiC(0001)/SiO2 interfaces. Our electrically detected-magnetic-resonance spectroscopy and first-principles calculations demonstrate that this center, which we name “the PbC center,” is formed at a carbon adatom on the 4H-SiC(0001) honeycomb-like structure. The PbC center (Si3≡C-, where “-” represents an unpaired electron) is determined to be a just carbon version of the famous Pb center (Si dangling-bond center, Si3≡Si-) at Si(111)/SiO2 interfaces because we found close similarities between their wave functions. The PbC center acts as one of the major interfacial traps in 4H-SiC(0001) metal-oxide-semiconductor field-effect transistors (MOSFETs), which decreases the free-carrier density and the field-effect mobility of 4H-SiC(0001) MOSFETs. The formation of the PbC centers has the role of reducing the oxidation-induced strain, similar to the case of the formation of the Pb centers.